Liposome-Encapsulated Hemoglobin Enhances Chemotherapy to Suppress Metastasis in Mice

Abstract

Liposome-encapsulated hemoglobin with high O2 -affinity (P50 O2 = 10 mm Hg, h-LEH) was reported to enhance tumor radiosensitivity. We hypothesize that targeted O2 delivery to tumor hypoxia by h-LEH may also enhance chemotherapy to suppress tumor growth and metastasis in mice. Doxorubicin (DXR; 0.5 or 2 mg/kg i.p.) or S-1 (4 or 8 mg/kg orally) alone or in combination with h-LEH (5 mL/kg i.v.) was administered for 2 weeks to C57BL/6N mice inoculated with Lewis Lung Carcinoma (LLC) in the leg. After the 2-week therapy in six treatment groups, mice were sacrificed for quantitative assessment of tumor growth and lung metastasis. The tumor was then evaluated for its expression of hypoxia-inducible factor-1α (HIF-1α) and matrix metallopoteinase-2 (MMP-2) activity. Combined use of h-LEH and chemotherapeutic agents (DXR or S-1) showed no additional enhancement on suppression of the tumor growth over the chemotherapeutic agent alone. However, the combination use of h-LEH significantly suppressed the number and total area of metastatic colonies in the lung compared with each chemotherapeutic agent alone. Although HIF-1α expression and MMP-2 activity in the original tumor was significantly suppressed in the groups of mice treated with either DXR or S-1 alone, the addition of h-LEH to either agent showed further enhancement of oxygen-mediated degradation of HIF-1α and suppression of MMP-2 activity. Although the addition of h-LEH to DXR or S-1 had little effect on original LLC tumor growth, it significantly enhanced suppression of lung metastasis in mice.

Artificial Oxygen Carrier to Regulate Hypoxic Signal Transduction

“…It has been our consistent observation that liposome‐encapsulated hemoglobin (LEH), specifically with high O 2 affinity ( h ‐LEH, P 50 O 2 = 8–17 mm Hg), has been associated with suppressed inflammation to promote wound healing , reduce damage after ischemia/reperfusion , and enhance antitumor therapies . Whereas LEH with low O 2 affinity ( l ‐LEH, P 50 O 2 = 40–50 mm Hg) was able to maintain O 2 delivery as a whole in rabbits under hemorrhagic shock, it was not associated with improved peripheral perfusion or extended survival .…”

“…Although AOC with high O 2 affinity promotes targeted O 2 delivery , subsequent mechanism(s) remained unclear. As a clue for clarifying the link between O 2 delivery to hypoxic cells and subsequent tamed inflammation, unique observations are presented in this issue regarding the presence of O 2 promoting degradation of hypoxia‐inducible factor 1‐alfa (HIF‐1α) by O 2 ‐dependent hydroxylation (Fig. A).…”

“…Not only in hypoxic somatic cells but also in tumor cell oxygenation was it demonstrated in a mouse model using near‐infrared spectroscopy that tumor Hb saturation increased in the order of intravenous h ‐LEH, homologous RBC, and l ‐LEH. Combined use of h ‐LEH‐enhanced radiotherapy for tumor growth and strengthened chemotherapy of metastasis , when metastatic foci, HIF‐1α accumulation as well as matrix‐metalloproteinase 2 (MMP2) expression (Fig. A) were all suppressed in mice treated with h ‐LEH alone or in combination with chemotherapeutic agents.…”

Artificial Blood- A Game Changer for Future Medicine: Where are we Today?

“…It has been reported that this encapsulation strategy can increase plasma retention time. However, unwanted immune interactions may happen from the liposome capsule [9]. As a new strategy, microcapsulation of hemoglobin shed light over creating real artificial red cells including the essential enzymes that act for the reduction of ischemia reperfusion injury and solve problems associated with methaemoglobin formation [10].…”

New Approaches in Commercial Development of Artificial Oxygen Carriers

“…With advancements in science, many strategies to control Hb's natural vasoconstrictive potential are now available. Encapsulation, PEGylation, CO-saturation, S-nitrosylation, or incorporation of ATP and adenosine are only a few examples of the strategies being implemented by artificial oxygen carrier developers (7,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). These strategies are evolving, and more concepts are on the way.…”